The goal of this project is to determine, in the context of visual search and classification tasks, the degree of age-related change in different forms of attentional functioning. The project is also concerned with the potential contribution of mild essential hypertension to age-related cognitive changes. The proposed experiments will involve measuring subjects' reaction time and accuracy for decisions regarding different types of visual displays. Experiments 1-6 will test the hypothesis that, as perceptual load is increased, disruption of performance from task-irrelevant information (flankers) will decline more for young adults that for older adults. This hypothesis will be assessed under conditions of varying display size (Experiment 1), perceptual discriminability (Experiment 2) memory load (Experiment 3), target location predictability (Experiment 4), and response-correlated flankers (Experiments 5 and 6). Experiments 7-13 will investigate the allocation of attention. Experiments 7-8 will determine whether there is an age-related change in the spatial distribution of attention. Experiments 9-12 will use the subadditivity diagnostic and analysis of different levels of stochastic dominance to test a model in which the shift of attention between display positions is serial but distance-independent. Experiment 13 will examine age differences in the ability to guide search on the basis of target-relevant features. Experiment 14 will compare the performance of hypertensive and normotensive individuals in visual search performance, to test the hypothesis that the interaction between age and hypertensive status is related to the memory demands of the task. Data from the present project will contribute to an improved account of the age-related changes in attentional functioning in healthy individuals, and of the potential role of hypertension in age-related cognitive change.